This invention relates to a method and apparatus for boring an underground lateral hole of relatively small diameter, such as a lateral hole for laying underground tubes such as, for example, gas pipes, water pipes, etc., or tubes for power-cables, optional or electrical transmission lines, and a lateral hole for draining water.
Previously, to bore an underground lateral hole of relatively small diameter a lateral hole boring apparatus is placed in a vertical hole extending downwardly from the surface of the ground, so that the operator entering the vertical hole operates the lateral hole boring apparatus while manually coupling a plurality of augers to each other.
This previously proposed excavation process requires boring a vertical hole of a size large enough for the operator to enter and stay therein for performing necessary operations, and, consequently, a large volume of earth must be removed from under the ground to form the vertical hole, thereby resulting in increasing the overall construction time, labor and expenses.
When gas pipes, water pipes, etc., are laid underground, an open-cut process may be employed without boring a lateral hole underground. When work is done to connect to an existing main a new gas pipe for supplying city gas from the main to a property or other establishment, the present practice is to excavate a square vertical hole of about one square meter which leads from the surface of a road which may be paved with asphalt and macadam to the position in which the main is laid. Then, a lateral ditch is dug which extends from the vertical hole to the property to which city gas, water or transmission line is desired to be supplied, and the worker enters the vertical hole to perform the work of connecting a new pipe to the main by connecting joints. Thereafter, a temporarily repairing process is employed to dump the sand into the hole and ditch and pave the road with asphalt, to keep traffic in safe and normal state. After lapse of several days, full-scale road repairing work is done under the supervision of officials responsible for maintaining the road safe for travel, to restore the road to the original conditions prevailing before the work for laying the public utility pipe was undertaken.
The above-described proposed process requires excavation of a large scale to be performed to excavate the vertical hole and lateral ditch in the road thereby raising the problem that the process of excavating, back filling and repairing is time-consuming because the area of the hole and ditch is very large. Additionally, the process requires a large workforce and is expensive to perform. Since the road is torn up on a large scale, the requirements to maintain an uninterrupted flow of traffic and to maintain the road in conditions conforming to the required safety standards must be met, so that repair work should be done twice or temporary repair and full-scale repair should be performed one after the other, as described hereinabove. This further increases the overall costs, time, and workforce necessary to perform the process. More specifically, expenses for doing civil engineering work to lay a new pipe account for 80% of the total expenses, and the period of time required to do the work is seven to ten days from a time the work is commenced to a time the full-scale repair is completed.
The aim underlying the present invention essentially resides in avoiding the problems of the prior art and, for this purpose, a method and apparatus for boring an underground lateral hole is provided which are capable of reducing the time, expenses and workforce required for boring the lateral hole.
Another object of the present invention resides in providing a method and apparatus for an underground lateral hole which are capable of reducing the time, expenses and workforce required for laying pipes underground when used for this purpose.
A still further object of the present invention resides in providing an apparatus for boring an underground lateral hole which makes it possible to avoid the occurrence of a situation in which excavation might be made impossible by objects lying underground.
A further object of the present invention resides in providing an apparatus for boring an underground lateral hole which is provided with auger attaching and detaching means constructed such that attaching and detaching of augers can be readily performed and the requirement of a space for performing the auger attaching and detaching operation does not militate against a reduction in the size of a vertical hole.
In accordance with the present invention, a method of boring an underground lateral hole comprises the steps of preparing a vertical hole of desired depth extending from the surface of the ground into the earth; preparing a lateral hole boring apparatus with a leading auger of a length smaller than the diameter of the vertical hole, and a plurality of coupling augers each of a length smaller than the diameter of the vertical hole. The leading auger is then attached to the lateral hole boring apparatus outside the vertical hole and the lateral hole boring apparatus equipped with the leading auger is lowered into the vertical hole and stopped in a predetermined position in the vertical hole. The lateral hole boring apparatus is then manipulated from the ground level to drive and advance the leading auger to bore a lateral hole and the driving and advancing of the leading auger is stopped when the lateral hole has reached a predetermined length commensurate with the length of the leading auger. The lateral hole boring apparatus is then manipulated from the ground level to detach the leading auger from the lateral hole boring apparatus and the lateral hole boring apparatus is lifted above the vertical hole while leaving the leading auger in the lateral hole. One of the coupling augers is coupled to the lateral hole boring apparatus outside the vertical hole and the lateral hole boring apparatus, equipped with the coupling auger, is lowered into the vertical hole again until it reaches the predetermined position. The lateral hole boring apparatus is manipulated from the ground level to connect the coupling auger to the leading auger left behind in the lateral hole, and the aforesaid above-described steps of manipulating, stopping, lifting and lowering are repeated until the lateral hole has reached a predetermined final length.
Additionally, in accordance with the present invention, it is also possible during the step of manipulating the lateral hole boring apparatus from the ground level, after the lateral hole of the predetermined final length has been formed, to rearwardly move the leading auger and all the coupling augers disposed in the lateral hole a distance corresponding to the length of one coupling auger and to manipulate the lateral hole boring apparatus from the ground level to detach the extremity trailing auger from the rest of the augers, as well as to lift the lateral hole boring apparatus equipped with the extremity trailing auger above the vertical hole while leaving the rest o the augers in the lateral hole, and detach the extremity trailing auger from the lateral hole boring apparatus outside the vertical hole. The lowering lateral hole boring apparatus is then lowered into the vertical hole again until it reaches the predetermined position and the lateral hole boring apparatus is manipulated from the ground level to make the lateral hole boring apparatus grasp the next trailing auger left in the lateral hole, with the above-described steps being repeated until all the augers including the leading auger have been withdrawn from the lateral hole and returned to the ground level.
Advantageously, the method of the present invention may further comprise the step of coupling a flexible pipe to a front end of the leading auger prior to rearwardly moving the leading auger and all the coupling augers left behind in the lateral hole following the formation of the lateral hole of the predetermined final length, whereby the pipe can be simultaneously inserted into the lateral hole as the augers are withdrawn from the lateral hole.
Preferably, the step of preparing a vertical hole of a desired depth extending from the surface of the ground down into the earth may comprise the step of forcing at least one cylindrical casing into the earth from the surface of the ground while excavating to form the vertical hole defined by the casing, but he leading auger and coupling augers each having a length smaller than the inner diameter of said casing.
In accordance with the apparatus of the present invention, frame means is provided which includes a support frame, and a guide frame connected to a lower end of said support frame, with an auger drive means for rotating augers mounted to the guide frame for travelling therealong. Travel means are supported by the frame means for travelling the auger drive means forwardly and rearwardly along the guide frame, with a rotary chuck means mounted to the auger drive means for releasably gripping a rear end of one of the augers and an operating means associated with the auger drive means, travel means, and rotary chuck means for permitting them to be manipulated by the operator on the ground level.
Preferably, the apparatus may further include at least one cylindrical casing for providing a vertical hole defined by an inner wall surface thereof, with the casing having first guide means located on the inner wall surface thereof, and second guide means, located on the support frame and cooperating with the first guide means to vertically guide the support frame in the casing during lowering and lifting thereof.
Preferably, the guide frame may be adjustably connected to the support frame in such a manner that the angle of tilting of the guide frame with respect to the support frame can be changed to thereby vary the angle of tilting of a path of travel for the auger drive means as desired with respect to the support frame.
It is also possible in accordance with the apparatus of the present invention to include auger attaching and detaching means capable of being manipulated by the operator on the ground level for attachment and detachment of a succeeding auger to and from at lest one preceding auger located in the bored lateral hole except at least its rear end.
In accordance with still further features of the invention, a lateral hole boring system as described abaove, including lifting and lowering means operative to move the lateral hole boring apparatus through the vertical hole between a predetermined position at the bottom of the vertical hole and a position above an open end of said vertical hole, with the lifting and lowering means being capable of being operated by an operator on the ground level.
Preferably, the lifting and lowering means may include winch means located over the open end of said vertical hole e and the winch means may be supported on a frame structure located on an upper end of a cylindrical casing defining the vertical hole. The frame structure may include a main frame body of substantially semi-cylindrical configuration, and the winch means may be supported on an upper end of the main frame body through a support frame.